The present invention relates to a gas supply regulation valve for controlling combustion in a kitchen oven, provided with a valve body with main flow and pilot flow conduits and which includes at least one thermostatic valve and a safety valve energised by a pilot flame thermocouple.
Thermostatic valves for kitchen ovens that control a main gas flow supplied from an outlet to an oven burner and a pilot flow supplied from a second outlet to an oven pilot burner that ignites the main burner are already known. The known valves include a thermostatic regulating valve sensitive to oven temperature, and also a thermoelectric safety valve located in first place from the gas inlet conduit to the valve. The safety valve built into the valve body is energised by a pilot flame sensing thermocouple, keeping open the intake of gas into the valve from the valve inlet conduit. For the initial opening prior to ignition of the pilot burner, the safety valve electromagnet armature needs to be seated by means of an axial thrust on a rotary valve actuating shaft. The safety valve shuts off the intake of gas entirely if its electromagnet armature is de-energised, either by extinction of the pilot flame or by means of an electric switch interposed in the thermocouple.
Some types of kitchen ovens need a pilot ignited all the time, even when the oven is not in use for cooking, for which they have a pilot flow passageway departing directly from a pilot chamber located behind the safety valve, so that in a rotational OFF position of the control knob the pilot flow is not cut off by the regulating valve. For this purpose, the manual control of the known standing pilot valves has an exclusive rotational PILOT position for the independent supply of a pilot flow in which it is situated for the opening of the safety valve initially. In the PILOT position the manual control shaft is permitted to make an axial forth and back movement to push the safety valve and open it. The shaft is provided with a side shoulder, which engages in a groove in the valve housing in the PILOT position, and the shaft thereby makes a longer forward movement.
A known valve structure like the one cited above is described in U.S. Pat. No. 5,203,588, but the known valve has a rotational OFF position of the control in which an additional pilot chamber shut-off valve is actuated. Other valve structures like that described in U.S. Pat. No. 5,407,128 although they do not use an additional valve to control the pilot flow, the pilot flow is shut off by means of an electric switch in series with the thermocouple, actuated by the manual control in its rotational OFF position.
An example of a thermostatic regulating valve structure for use in a kitchen oven is described in U.S. Pat. No. 4,765,536. This valve structure comprises a manual rotary valve with a tapering shut-off member and a thermostatic capsule valve with a capillary tube of expandable liquid, both in series. But this latter valve structure does not have a built-in safety valve controlling the pilot flow, because it uses a safety valve with an independent and separate pilot flame connected from the outside to the thermostatic valve.
The object of the present invention is to provide a thermostatic gas valve structure for a kitchen oven, provided with a thermoelectric safety valve and a pilot flow passageway independent of the rotational actuating shaft position, in order to maintain a standing supply to an oven pilot burner, even after the main flow is shut off when its use for cooking has terminated.
The valve structure comprises a thermostatic valve body with an actuating shaft and a manual rotary control knob, and with two outlet conduits for connection to two respective oven burners, wherein a second one of the outlet conduits is adapted to provide a standing pilot flow for connection to the oven pilot burner by means of a passageway that departs directly from the safety valve. Thus, the control OFF and PILOT indications, for shutting off the main flow and initial pilot burner ignition respectively, coincide at a single position of the actuating shaft, the shut-off of the pilot flow takes place solely by means of de-energising the safety valve, and the pilot flow is supplied independently of the control knob rotation movements.
The thermostatic valve structure of the present invention also provides means for manual actuating of the safety valve for initial ignition of the pilot burner by means of an actuating shaft provided with axial reciprocating movement to push the safety valve until it is held in the actuating position by the energising of the thermocouple. The thermostatic valve structure is provided with a front cover traversed by the actuating shaft, which is adapted so that the axial forward movement of the actuating shaft to open the safety valve achieves a long travel in the actuating shaft PILOT position only, in which it is no able to be rotated and so as to prevent the possibility of the main flow being supplied before the pilot flow is ignited.